Human leukocyte antigen (HLA) typing was performed on 55 Caucasian schizophrenic patients, who were subdivided into groups on the basis of clinical subtype, response to neuroleptic treatment, enlargement of the lateral ventricles, presence of increased prefrontal and/or parieto-occipital markings, and presence of reversed frontal and/or occipital lobe asymmetry. No observed differences in antigen frequencies between the group as a whole and controls or between any subgroup and the remaining group or controls remained significant after correction for the number of antigens tested.